Lubricating system for internal combustion engine, oil pan apparatus, and internal combustion engine

ABSTRACT

A valve system is disclosed herein. The valve system, in one arrangement, may comprise: a fluid pathway for transporting a fluid; a first valve operably coupled to the fluid pathway, the first valve comprising a first resilient element; a second valve operably coupled to the fluid pathway, the second valve comprising a second resilient element that is substantially identical to the first resilient element; wherein, when the first valve is in a closed state, the first resilient element is compressed to a first length so that the first valve opens at a first pressure; and wherein, when the second salve is in a closed state, the second resilient element is compressed to a second length so that the second valve opens at a second pressure, the first length is less than the second length such that the second pressure is less than the first pressure.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

The present application is a continuation application of U.S.Nonprovisional patent application Ser. No. 14/169,940, filed Jan. 31,2014, the entirety of which is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a valve system which may be used, forexample, in a lubrication system or other fluid transport systems.

BACKGROUND OF THE INVENTION

Lubricating systems for internal combustion engines are known. Incertain known lubricating systems, a lubricating oil drops to a basin ata bottom portion of a crankcase housing after lubricating one or moreportions of the internal combustion engine. The recovered oil is thenfed through an oil cooler where thermal energy is removed from the oiland the cooled oil is fed to an oil filter. After passing through theoil filter, the cooled oil is again introduced to the one or moreportions of the internal combustion engine in need of lubrication. Theoil then drops back to the basin, thereby completing the oil circuit forcyclical use.

In certain known oil lubricating systems, such as the one describedabove, oil pump output capacity, by design, significantly exceedslubricating demand under most, if not all engine operating conditionsand speeds. To prevent an excessive build-up of pressure (and resultingpump or other components damage) when oil supply exceeds oil demand, apressure relief valve is provided in the oil circuit immediatelydownstream of the oil pump and upstream of all other lubricating systemcomponents, including the oil cooler. Thus, if the oil pressure withinthe oil circuit builds up at the position of the pressure relief valve,the pressure relief valve will open, thereby alleviating the pressure bydischarging the oil back into the oil reservoir in the basin. Pressurebuildup can occur, for example, during engine startup when the oil iscold and has increased viscosity, in instances where the oil filter orother part of the oil circuit become blocked/clogged, and during most,if not all engine operating conditions when pump output exceedslubricating oil requirements of the engine. Thus, the pressure reliefvalve provides a mechanism by which the excessive pressure within theoil circuit is eliminated by dumping the oil back into the oilreservoir.

During engine cold start conditions, because the oil is dumped back intothe oil reservoir prior to flowing through the oil cooler, thetemperature of the oil in the oil reservoir will build up faster whenthe pressure relief valve is an open state. However, since the pressurerelief valve never returns to the fully closed state once normal engineoperating conditions are reached, the oil may not be adequately cooledprior to being reintroduced to the portions of the internal combustionengine in need of lubrication.

Thus, a need exists for a lubricating system for an internal combustionengine that can both relieve oil pressure within the oil circuit asneeded while at the same time increasing the amount of thermal energyremoved from the oil.

SUMMARY OF THE INVENTION

According to one aspect of the present disclosure, a lubricating systemfor an internal combustion engine is disclosed that includes a dualpressure relief arrangement, wherein a first pressure relief valve and asecond pressure relief valve are operably coupled to the oil circuit.The first pressure relief valve may be operably coupled to the oilcircuit upstream of the oil cooler and configured to open so as to allowoil to return to the oil reservoir without passing through the oilcooler. The second pressure relief valve may be operably coupled to theoil circuit downstream of the oil cooler and configured to open so as toallow oil to return to the oil reservoir after passing through the oilcooler. The first pressure relief valve may be configured to open at afirst predetermined pressure while the second pressure relief valve maybe configured to open at a second predetermined pressure, the secondpredetermined pressure being less than the first predetermined pressure.An oil pump may be provided to drive the oil through the oil circuit.

In one aspect, the invention can be a lubrication system for an internalcombustion engine, the lubrication system comprising: an oil cooler; anoil cooler supply passage for delivering oil to an inlet of the oilcooler from an oil reservoir; an oil cooler outlet passage fordelivering oil from an outlet of the oil cooler to one or more portionsof the internal combustion engine to be lubricated; a first pressurerelief valve operably coupled to the oil cooler supply passage, thefirst pressure relief valve configured to open at a first predeterminedpressure to allow oil in the oil cooler supply passage to return to theoil reservoir without passing through the oil cooler; and a secondpressure relief valve operably coupled to the oil cooler outlet passage,the second pressure relief valve configured to open at a secondpredetermined pressure to allow oil in the oil cooler outlet passage toreturn to the oil reservoir after passing through the oil cooler, thesecond predetermined pressure being less than the first predeterminedpressure.

In another aspect, the invention can be an internal combustion enginethat includes the lubrication system set forth above.

In a further aspect, the invention can be an oil pan apparatus for aninternal combustion engine comprising: a body forming a basin: an oilreservoir in the basin; a first pressure relief valve operably coupledto an oil cooler supply passage to allow oil in the oil cooler supplypassage to return to the oil reservoir without passing through an oilcooler; a second pressure relief valve operably coupled to an oil cooleroutlet passage to allow oil in the oil cooler outlet passage to returnto the oil reservoir after passing through the oil cooler; and the firstpressure relief valve configured to open at a first predeterminedpressure and the second pressure relief valve configured to open at asecond predetermined pressure, the second predetermined pressure beingless than the first predetermined pressure.

In an even further aspect, the invention can be an oil pan apparatus foran internal combustion engine comprising: a body forming a basin forholding an oil reservoir; a first pressure relief valve operably coupledto an oil cooler supply passage to allow oil in the oil cooler supplypassage to return to the oil reservoir without passing through an oilcooler; a second pressure relief valve operably coupled to an oil cooleroutlet passage to allow oil in the oil cooler outlet passage to returnto the oil reservoir after passing through the oil cooler; and the firstpressure relief valve configured to open at a first predeterminedpressure and the second pressure relief valve configured to open at asecond predetermined pressure, the second predetermined pressure beingless than the first predetermined pressure.

In a still further aspect, the invention can be an oil pan apparatus foran internal combustion engine comprising: a body forming a basin forholding an oil reservoir; an oil pump in the basin, the oil pump havingan inlet in fluid communication with the oil reservoir and an outlet; anoil filter mounting element; an oil cooler supply passage formed in thebody extending from the outlet of the oil pump to a first opening in anouter surface of the body; a pre-filter section of an oil cooler outletpassage formed in the body and extending from a second opening in theouter surface of the body to a third opening in the outer surface of thebody, the third opening positioned adjacent to or on the oil filtermounting element; a post-filter section of the oil cooler outlet passageformed in the body and extending from a fourth opening in the outersurface of the body to a fifth opening in the outer surface of the body,the fourth opening positioned adjacent to or on the oil filter mountingelement; a first pressure relief valve located within the basin, thefirst pressure relief valve operably coupled to the oil cooler supplypassage to allow oil in the oil cooler supply passage to return to theoil reservoir without passing through the third opening; and a secondpressure relief valve located within the basin, the second pressurerelief valve operably coupled to the pre-filter section of the oilcooler outlet passage to allow oil in the pre-filter section of the oilcooler outlet passage to return to the oil reservoir without passingthrough the fourth opening.

In a yet further aspect, the invention can be an internal combustionengine comprising the oil pan apparatus described above.

In an even further aspect, the invention can be valve system comprising:a fluid pathway for transporting a fluid; a first valve operably coupledto the fluid pathway, the first valve comprising a first resilientelement; a second valve operably coupled to the fluid pathway, thesecond valve comprising a second resilient element that is substantiallyidentical to the first resilient element; wherein, when the first valveis in a closed state, the first resilient element is compressed to afirst length so that the first valve opens at a first pressure; andwherein, when the second valve is in a closed state, the secondresilient element is compressed to a second length so that the secondvalve opens at a second pressure, the first length is less than thesecond length such that the second pressure is less than the firstpressure.

In another aspect, the invention may be a valve system comprising: afluid pathway for transporting a fluid; a first valve operably coupledto the fluid pathway, the first valve comprising a first resilientelement having a first spring constant; a second valve operably coupledto the fluid pathway, the second valve comprising a second resilientelement having a second spring constant; the second spring constantbeing substantially the same as the first spring constant; wherein, whenthe first valve is in a closed state, the first resilient element isdeformed a first degree so that the first valve opens at a firstpressure; and wherein, when the second valve is in a closed state, thesecond resilient element is deformed a second degree so that the secondvalve opens at a second pressure that is different than the firstpressure.

In a further aspect, the invention may be a valve system comprising: abody; a fluid pathway for transporting a fluid, the fluid pathwaycomprising a first section formed in the body and a second portionformed in the body; a first valve operably coupled to the first sectionof the fluid pathway, the first valve comprising a first valve seatintegrally formed as part of the body; and a second valve operablycoupled to the second section of the fluid pathway, the second valvecomprising a second valve seat integrally formed as part of the body.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred aspects of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a fluid circuit schematic of a lubricating system for aninternal combustion engine according to the present invention;

FIG. 2 is a schematic of an oil pan apparatus, in which an embodiment ofthe lubricating system of FIG. 1 has been incorporated, according to thepresent invention;

FIG. 3 is a perspective view a structural embodiment of the oil panapparatus of FIG. 2;

FIG. 4 is a close-up view of area IV of FIG. 3;

FIG. 5 is a left-side plan view of the oil pan apparatus of FIG. 2;

FIG. 6 is a top plan view of the oil pan apparatus of FIG. 2;

FIG. 7 is a perspective view of the oil pan apparatus of FIG. 2 whereinthe oil pump cover plate is shown in phantom so that the first andsecond pressure relief valves are visible;

FIG. 8 is a close-up view of area VIII of FIG. 7;

FIG. 9 is a vertical cross-sectional view of the oil pan apparatus takealong view IX-IX of FIG. 6;

FIG. 10 is a horizontal cross-sectional view of the oil pan apparatustake along view X-X of FIG. 5;

FIG. 11 is a horizontal cross-sectional view of the oil pan apparatustake along view XI-XI of FIG. 5;

FIG. 12 is a vertical cross-sectional view of the oil pan apparatus takealong view XII-XII of FIG. 6;

FIG. 13A is a close-up view of area XIII of FIG. 12 in which theresilient elements of the first and second pressure relief valves arecompressed by the oil pump cover plate; and

FIG. 13B is a close-up view of area XIII of FIG. 12 in which the oilpump cover plate has been removed so that it can be seen that theresilient elements of the first and second pressure relief valves areidentical coil springs.

DETAILED DESCRIPTION OF EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

The description of illustrative embodiments according to principles ofthe present invention is intended to be read in connection with theaccompanying drawings, which are to be considered part of the entirewritten description. In the description of embodiments of the inventiondisclosed herein, any reference to direction or orientation is merelyintended for convenience of description and is not intended in any wayto limit the scope of the present invention. Relative terms such as“lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,”“down,” “top” and “bottom” as well as derivative thereof (e.g.,“horizontally,” “downwardly,” “upwardly,” etc.) should be construed torefer to the orientation as then described or as shown in the drawingunder discussion. These relative terms are for convenience ofdescription only and do not require that the apparatus be constructed oroperated in a particular orientation unless explicitly indicated assuch. Terms such as “attached,” “affixed,” “connected,” “coupled,”“interconnected,” and similar refer to a relationship wherein structuresare secured or attached to one another either directly or indirectlythrough intervening structures, as well as both movable or rigidattachments or relationships, unless expressly described otherwise.Moreover, the features and benefits of the invention are illustrated byreference to the exemplified embodiments. Accordingly, the inventionexpressly should not be limited to such exemplary embodimentsillustrating some possible non-limiting combination of features that mayexist alone or in other combinations of features; the scope of theinvention being defined by the claims appended hereto.

Referring first to FIG. 1, a lubrication system 500 for an internalcombustion engine according to the present invention is illustrated. Thelubrication system 500 generally comprises, in fluid coupling, an oilreservoir 510, an oil pump 520, an oil cooler 530, and an oil filter540. While the oil reservoir 510 is illustrated multiple times in FIG.1, the oil reservoir 510 may be a single body of oil. The oil reservoir510 may, however, be divided into a plurality of sub-reservoirs of oilthat are in fluid communication with one another in certain otherarrangements. The lubrication system 500 further comprises a firstpressure relief valve 550 and a second pressure relief valve 560.

The lubrication system 500 delivers oil from the oil reservoir 510 toone or more portions 100 of the internal combustions that are to belubricated (generically illustrated as box 100 in FIG. 1). The one ormore portions 100 of the internal combustion can include, withoutlimitation, the crankshaft, the crankshaft bearings, the connecting rod,the connecting rod bearings, the camshaft, the camshaft bearings, thecylinder block, the cylinder head, pistons (via spray devices known aspiston squirters), hydraulic valve lifters, and valve train components.After the oil is delivered by the lubrication system 500 to the portions100 of the internal combustion engine, the oil returns to the oilreservoir 510, thereby completing an oil circuit. The oil can return tothe oil reservoir 510 via a gravity feed (i.e., allowing the oil to dropback to the oil reservoir). Alternatively, the oil can return to the oilreservoir 510 through one or more oil return passages 545 (see FIG. 2)in which pressure from the oil pump 520 generates flow in the oil returnpassages. Of course, combinations of gravity feed and forced feed may beutilized.

The oil pump 520 comprises an inlet 521 that is in fluid communicationwith the oil reservoir 510 and an outlet 522. The oil pump 510 may be atrochoid type pump (as shown in FIG. 10). Alternatively, the oil pump510 may be any type of positive displacement pump (rotary orreciprocating), impulse pump, velocity pump, or gravity pump. Suitabletypes of positive displacement pumps may include, without limitation,gear pumps, screw pumps, rotary vane pumps, progressing cavity pumps,roots-type pumps, progressive cavity pumps, rotary gear pumps, pistonpumps, diaphragm pumps, hydraulic pumps, regenerative (peripheral)pumps, peristaltic pumps, rope pumps, flexible impeller pumps,rotolliptic pumps, and plunger pumps. Suitable types of velocity pumpsmay include, without limitation, centrifugal pumps, radial-flow pumps,axial-flow pumps, mixed-flow pumps, and eductor-jet pumps. The exacttype of oil pump utilized will be determined by: (1) the requirements ofthe lubricating system 500, such as system flow and pressurerequirements; (2) the location of the oil pump 500 relative to theengine block; (3) the position of the oil pump 500 in the oil circuitrelative to the other components thereof; (4) the driving mechanismutilized, space available within engine, and cost of the system.

The lubricating system 500 further comprises an oil cooler supplypassage 525 that fluidly couples the oil pump 520 to the oil cooler 530.More specifically, the oil cooler supply passage 525 fluidly couples theoutlet 522 of the oil pump 520 to an inlet 531 of the oil cooler 530.Thus, when the oil pump 520 is operating, oil in the oil reservoir 510is drawn into the inlet 521 of the oil pump 520 and expelled from theoutlet 522 of the oil pump 520. This oil is then delivered from theoutlet 522 of the oil pump 520 to the inlet 531 of the oil cooler 530via the oil cooler supply passage 525 (assuming that the first pressurerelief valve 550 is closed, as discussed in greater detail below).

The oil cooler 530 is a heat exchanger that can transfer thermal energybetween the oil flowing therethrough and a coolant fluid. Asexemplified, the oil cooler 530 transfers thermal energy from the oilflowing therethrough to the coolant fluid. Any suitable coolant fluidcan be utilized by the oil cooler 530. For example, the coolant may beair that flows over heat exchange fins of the oil cooler 530 or a liquidengine coolant that is delivered to the oil cooler 530 via a separateline/circuit. As the oil flows through oil cooler 530, which may bethrough a tortuous path, thermal energy is transmitted from the oil tothe coolant fluid, thereby reducing the temperature of the oil. Thus,the oil has a hot temperature at the inlet 531 of the oil cooler 530 anda cold temperature 532 at the outlet 532 of the oil cooler 530, whereinthe hot temperature is greater than the cold temperature. Alternatively,the oil cooler 530 may transfer thermal energy from the coolant fluid tothe oil flowing therethrough in cases where it is desired to heat theoil.

The lubricating system 500 further comprises an oil cooler outletpassage 535 that fluidly couples the oil cooler 530 to the portions 100of the internal combustion engine that are to be lubricated. Duringoperation of the oil pump 522 (assuming that the second pressure reliefvalve 550 is closed, as discussed in greater detail below), the oilcooler outlet passage 535 delivers oil from the outlet 532 of the oilcooler 530 to the portions 100 of the internal combustion engine to belubricated. Thus, oil that has been cooled by the oil cooler 530 isprovided to the portions 100 of the internal combustion engine.

The oil filter 540 is operably coupled to the cooler outlet passage 535between the outlet 532 of the oil cooler 530 and the portions 100 of theinternal combustion engine. The oil filter 540 comprises a filter media543, an inlet chamber 541, and an outlet chamber 542. The inlet andoutlet chambers 541, 542 are located on opposite sides of the filtermedia 543. Thus, in order for oil to flow from the inlet chamber 541 tothe outlet chamber 542, the oil must pass through the filter media 543,thereby filtering the oil by removing particulate and othercontaminants. The oil filter 540 may be a cartridge type oil filter or aspin-on type oil filter, as is known in the art (discussed in greaterdetail in relation to FIG. 2). Other types of oil filters may bealternatively utilized, including without limitation centrifuge filters,gravity filters, and magnetic filters.

The oil filter 540 delineates the cooler outlet passage 535 into anpre-filter section 535A and a post-filter section 535B. It should benoted that the terms “pre-filter section” and “post-filter section” areintended to be relative to the oil filter 540. It is to be understoodthat the oil circuit may comprise additional filters at other locations.Thus, it is possible that the oil in the pre-filtered section has beenpreviously filtered elsewhere in the oil circuit.

The pre-filter section 535A of the oil cooler outlet passage 535 extendsfrom the outlet 532 of the oil cooler 530 to an inlet side of the filtermedia 543 of the oil filter 540. The pre-filter section 535A may beconsidered to include the inlet chamber 541 of the oil filter 540. Thepost-filter section 535B of the oil cooler outlet 540 extends from anoutlet side of the filter media 543 of the oil filter 540 to theportions 100 of the internal combustion engine to be lubricated. Thepost-filter section 535B may considered to include the outlet chamber542 of the oil filter 540. While the oil filter 540 is exemplified asbeing located downstream of the oil cooler 530, the oil filter 540 maybe located upstream of the oil cooler 530, for example between the oilpump 520 and the oil cooler 530, or before the oil pump 520, in otherarrangements. If an oil filter were located between the oil pump 520 andthe oil cooler 530, such an oil filter 540 may be a relatively coarsescreen that would keep large particles from getting into the first orsecond pressure relief valves 550, 560, or the oil cooler 530 itself,should the oil pump 520 start to break down and discharge relativelylarge pieces of metal. Additional oil filters may be included ifdesired. One such filter is a relatively coarse screen that may belocated between the oil reservoir and the inlet to the oil pump.

The first pressure relief valve 550 is operably coupled to the oilcooler supply passage 525. More specifically, in the exemplifiedarrangement, the first pressure relief valve 550 is operably coupled tothe oil cooler supply passage 525 via a first pressure relief passage526 that is in fluid communication with the oil cooler supply passage525. In alternate arrangements, the first pressure relief valve 550 maybe operably coupled directly to the oil cooler supply passage 525. Thefirst pressure relief valve 550 is configured to be normally closed andto open at a first predetermined pressure, thereby allowing oil in theoil cooler supply passage 525 to return to the oil reservoir 510 withoutpassing through the oil cooler 530. Thus, when the pressure of the oilwithin the oil cooler supply passage 525 is at or above the firstpredetermined pressure, the first pressure relief valve 550 transitionsfrom a closed-state to an open state, thereby allowing the oil withinthe oil cooler supply passage 525 to escape from the oil cooler supplypassage 525 through the first pressure relief valve 550 and back intothe oil reservoir 510, thereby relieving pressure within the oilcircuit. The first pressure relief valve 550 will remain in the openstate until the pressure of the oil within the oil cooler supply passage525 falls below the first predetermined pressure. However, because thefirst pressure relief valve 550 is biased into the closed state, thefirst pressure relief valve 550 will automatically transition from theopen state to the closed state upon the pressure of the oil within theoil cooler supply passage 525 falling below the first predeterminedpressure.

The second pressure relief valve 560 is operably coupled to the oilcooler outlet passage 535. In the exemplified arrangement, the secondpressure relief valve 560 is operably coupled to the oil cooler outletpassage 535 via a second pressure relief passage 536 that is in fluidcommunication with the oil cooler outlet passage 535. In alternatearrangements, the second pressure relief valve 560 may be operablycoupled directly to the oil cooler outlet passage 535.

The second pressure relief valve 560 is operably coupled to the oilcooler outlet passage 535 at a position between the outlet 532 of theoil cooler 530 and the portions 100 of the internal combustion engine tobe lubricated. As exemplified, the second pressure relief valve 560 maybe operably coupled to the pre-filter section 535A of the oil cooleroutlet passage 535 (i.e., at a position between the outlet 532 of theoil cooler 530 and the filter media 543 of the oil filter 540). In suchan arrangement, opening of the second pressure relief valve 560 allowsoil in the oil cooler outlet passage 535 to return to the oil reservoir510 after passing through the oil cooler 530 but without passing throughthe filter media 543. In alternate arrangements, the second pressurerelief valve 560 may be operably coupled to the post-filter section 535Bof the oil cooler outlet passage 535 (i.e., at a position downstream ofthe filter media 543 of the oil filter 540).

The second pressure relief valve 560 is configured to be normally closedand to open at a second predetermined pressure, thereby allowing oil inthe oil cooler outlet passage 535 to return to the oil reservoir 510after passing through the oil cooler 530. Thus, when the pressure of theoil within the oil cooler outlet passage 535 is at or above the secondpredetermined pressure, the second pressure relief valve 560 transitionsfrom a closed-state to an open state, thereby allowing the oil withinthe oil cooler outlet passage 535 to escape from the oil cooler outletpassage 535 through the second pressure relief valve 560 back into theoil reservoir 510, thereby relieving pressure within the oil circuit.The second pressure relief valve 560 will remain in the open state untilthe pressure of the oil within the oil cooler outlet passage 535 fallsbelow the second predetermined pressure. However, because the secondpressure relief valve 560 is biased into the closed state, the secondpressure relief valve 560 will automatically transition from the openstate to the closed state upon the pressure of the oil within the oilcooler outlet passage 535 falling below the second predeterminedpressure. The second predetermined pressure may be less than the firstpredetermined pressure.

The second predetermined pressure may be selected so that it is ensuredthat the quantity of oil typically required for the particular internalcombustion engine in which the lubrication system 500 is integrated canbe cleaned through the oil filter 540 and delivered to the one or moreportion 100 through the lubricating passages. The second predeterminedpressure may, in certain instances, be established by a series of enginedevelopment tests in which the pressure in the furthest lubricatingpoint of the one or more portions 100 is monitored to ensure that oilpressure at this further lubricating point does not drop below a loweroil pressure threshold required to ensure adequate oil flow to thisfurthest lubrication point. If it is determined that for the selectedsecond predetermined pressure that the oil pressure at this furtherlubricating point drops below the minimum threshold, the secondpredetermined pressure is adjusted upward to ensure adequate oil flow tothis furthest lubrication point. Increasing the second pressure settingto ensure adequate oil flow to this furthest lubrication point isbalanced with an upper oil pressure threshold at which external leakagefrom the lubrication system 500 is determined to occur (such as throughthe crankshaft main bearing or any other seals in the lubrication system500).

The first predetermined pressure may be selected to ensure that fulloutput flow of the oil pump 520, at the highest normal operating speedof the internal combustion engine, flows through the oil cooler 530 whenthe oil is at an ordinary engine operating temperature, such as when theoil temperature is above 100° F. in certain embodiments. The firstpredetermined pressure may, in certain regards, be dependent on the typeof oil cooler 530 utilized in the lubrication system.

A number of bench tests were run using different oil cooler designs atvarious flow rates and oil temperatures. It was determined for certainoil cooler designs, 20 psi was capable of delivering upwards of 3 gpmoil flow at oil temperatures of between 100° F. and 150° F. This meansthat setting the first pressure setting at about 20 psi higher than thesecond pressure setting, the first relief valve 550, at high normalengine speeds, will close at oil temperatures between 100° F. and 150°F. As a result, full output flow of the oil pump 520 flows through theoil cooler 530. Adjusting the ratio of the first to second pressuresettings will affect the engine operating temperatures at variousoperating conditions.

The second predetermined pressure may be in a range of 10 to 30 psi inone preferred arrangement, 15 to 25 psi being more preferred, and mostpreferably about 20 psi. The second pressure relief valve 560 may,however, be configured to open at other pressures as is known in theart. The exact pressure selected for the second predetermined pressuremay be based on a variety of consideration, including the desiredoperating parameters of the lubricating system 500, the type of oilbeing utilized, and the desired engine operating conditions.

The first predetermined pressure may be in a range of 35 to 55 psi inone preferred arrangement, and more preferably about 40 psi. The firstpressure relief valve 550 may, however, be configured to open at otherpressures as is known in the art. The exact pressure selected for thefirst predetermined pressure may be based on a variety of consideration,including the desired operating parameters of the lubricating system500, the type of oil being utilized, and the desired engine operatingconditions.

More specifically, the first and second predetermined pressures may beselected so that a ratio of the second predetermined pressure to thefirst predetermined pressure is less than 0.8:1, and more preferablyless than about 0.6:1. In other arrangements, the first and secondpredetermined pressures may be selected so that a ratio of the secondpredetermined pressure to the first predetermined pressure is in a rangeof about 0.4:1 to 0.6:1. In one specific arrangement, the first andsecond predetermined pressures may be selected so that a ratio of thesecond predetermined pressure to the first predetermined pressure isabout 0.5:1.

Suitable types of valves for the first and second pressure relief valves550, 560 include, without limitation, ball check valves, disk checkvalves, sleeve-type relief valves, poppet-type relief valves. The firstand second pressure relief valves 550, 560 can be the same type of valveor can be different types of valves. In one arrangement, the first andsecond pressure relief valves 550, 560 are the same type of valve. Inone specific arrangement, the first and second pressure relief valves550, 560 are structurally substantially identical to one another buthave resilient elements that are compressed to different lengths intheir normal states, thereby resulting in the first and second pressurerelief valves 550, 560 having different actuation pressures (discussedin greater detail below).

The first pressure relief valve 550 relieves pressure within the oilcircuit primarily during cold engine startups when the oil is viscous.The first pressure relief valve 550 may not open (or rarely open) duringnormal engine operating conditions (absent a major blockage or othercritical pressure-inducing event). To the contrary, the second pressurerelief valve 560 will open as necessary during normal engine operatingconditions to relieve pressure in the oil circuit as needed. Forexample, if the oil pump 520 is a fixed displacement design, sized todeliver adequate lubrication at lowest operating speed of say 1200 rpm(low idle), then the oil pump output flow at the maximum operating speedof say 4000 rpm (high speed no load) will be significantly more than canflow through the lubrication passages with the secondary pressureavailable. Under those conditions, the second pressure relief valve 560will be open and a significant quantity of oil will be bypassed back tothe oil reservoir. As a result, the lubricating system 500 will maintainthe pressure within the oil circuit within acceptable levels by openingthe second pressure relief valve 560 while maintaining the firstpressure relief valve 550 closed, thereby continuously flowing oilthrough the oil cooler 530 during normal engine operating conditions.Thus, during normal engine operating conditions, the oil is dumped backinto the oil reservoir 510 only after passing through the oil cooler530. This allows the oil in the oil circuit to have a lower temperature(as compared to lubricating systems that dump the oil back into the oilreservoir without passing through the oil cooler). As a result, aninternal combustion engine utilizing the inventive lubricating system500 may show a decrease in operating temperature that is in a range of30° F. to 55° F., as compared to the same internal combustion engineutilizing a lubricating system that dumps the oil back into the oilreservoir without passing through the oil cooler.

Normal engine operating conditions vary significantly based upon theapplication for which the engine is used. For certain applications,engines may be rated at 3600 rpm, under full power, which is known as“wide open throttle” or WOT conditions. A typical commercial lawn mowingapplication will typically run at a lower engine speed range of 3200 to3400 rpm (lower speed generally reduces noise and improves fuelefficiency), under 30% to 40% WOT power conditions. Other applications,such as pumps and generators will typically run at 3600 rpm, and can runat higher power levels such as 50% to 60% WOT.

In order to maintain the desired flow characteristics within the oilcircuit under various engine conditions, the flow of the oil through thefirst and second pressure relief passages 526, 536 may be furthercontrolled by properly designing the outlets of the first and secondpressure relief passages 526, 536 to have effective cross-sectionalareas that control flow rates of the oil even when the first and/orsecond pressure relief valves 550, 560 are open. For example, the outletof the second pressure relief passage 536 may have an effectivecross-sectional area that is less than the effective cross-sectionalarea of the first pressure relief passage 526.

The effective cross-sectional areas of the first and second pressurerelief passages 526, 536 allow prediction of system operating pressurerelative to how much load the relief valve spring applies to the ballcheck (discussed in greater detail below). If the effectivecross-sectional area is too small for either of the first or secondpressure relief passages 526, 536, additional restriction is createdthat will increase system operating pressure higher than expected,especially under cold oil conditions. Thus, as discussed in greaterdetail below, the first pressure relief passage 526 may have twooutlets, as opposed to the second pressure relief passage 536 which hasa single relief valve outlet.

In the exemplified arrangement, the lubricating system 500 comprisesonly one oil pump 520. The same oil pump 520 drives the flow of oilthrough the oil cooler 530 and through the oil filter 540 when the firstand second pressure relief valves 550, 560 are closed. Thus, thelubricating system 500, in certain arrangements, is not be a dry sumplubrication system. However, in other arrangements, more than one oilpump 520 may be provided and operably coupled along the oil circuit asneeded to achieve the desired oil flow parameters.

Referring now to FIG. 2, an oil pan apparatus 200 according to thepresent invention is schematically illustrated. The oil pan apparatus200 generally comprises the lubricating system 500 of FIG. 1, which isincorporated into a body 201 that forms a basin 202. The body 201, asexemplified, is an oil pan for an internal combustion engine and forms aportion of the housing that forms the engine block. As used herein, thehousing of the engine block includes, without limitation, the oil pan,the crankcase, the cylinder block, and the cylinder head.

In the oil pan apparatus 200, certain components of the lubricatingsystem 500 have been formed into and/or or positioned within the body201 that forms the basin 202 which acts as the oil pan. While thelubricating system 500 will be described herein in relation to beingincorporated into the body 201, which forms the oil pan, the inventiveconcepts of the lubricating system 500 may be incorporated into aninternal combustion engine in a variety manners and/or positions. Forexample, the lubricating system 500 may be incorporated into the housingof the engine block at other locations, such as the crankcase, thecylinder block, the cylinder head, or combinations thereof. Moreover,while a certain subset of the components of the lubricating system 500will be exemplified herein as being positioned within or formed into thehousing of the engine block (specifically the body 201 of the oil pan inthe example), a different subset of the components of the lubricatingsystem 500 can be located within or formed into the housing of theengine block in other structural arrangements of the invention.

The body 201 comprises an upstanding wall 203 and a floor 204 thatcollectively form the basin 202. The body 201 may be an integrallyformed single component structure that can be formed by techniques suchas, without limitation, forging, machining, casting, injection molding,or combinations thereof. Suitable materials for forming the body 201include, without limitation, aluminum, cast iron, steel, thermoplasticpolymers, thermoset polymer, or combinations thereof.

The oil reservoir 510, the oil pump 520, the first pressure relief valve550 and the second pressure relief valve 560 are located within thebasin 202 of the body 201. The oil filter 540 is mounted to an outersurface 205 of the body 201, and specifically to an outer surface 205 ofthe upstanding wall 203. The oil filter 540 is a spin-type oil filterthat generally comprises a housing 544. The filter media 543 ispositioned within the housing 544 and divides the cavity of the housing544 into the inlet chamber 541 and the outlet chamber 542. The filtermedia 543 may be a hollow tubular structure such that when the filtermedia 543 is positioned within the housing 544, the inlet chamber 541 isan annular chamber located between the filter media 543 and an innersurface of the housing 544. The outlet chamber 542, in such anarrangement, may be formed by the inner surface of the filter media 543.In order to facilitate mounting of the oil filter 540 to the body 201,the housing 544 may have a cylindrical threaded portion (not shown) forthreadily engaging a boss 221 (FIG. 3) protruding from an outer surface205 of the body 201. In addition to, or instead of the spin-on filter,other types of oil filters 540 may be utilized in the oil circuit asdesired, such as a cartridge type. Additionally, the oil filter 540 maybe mounted to another part of the housing of the engine block, toanother part of the internal combustion engine, or to a chassis to whichthe internal combustion engine is mounted. Such filters may be referredto as remote mounted oil filters.

The oil cooler 530 is not mounted directly to the body 530 in theexemplified arrangement. Rather, the oil cooler 530 is indirectlymounted to the body 201 by an oil cooler inlet conduit 300 and an oilcooler outlet conduit 310 (shown in FIG. 3). In order to stabilize theoil cooler 530 to the internal combustion engine, the oil cooler 530 maybe mounted to another part of the housing of the engine block, toanother part of the internal combustion engine, or to a chassis to whichthe internal combustion is mounted. In another configuration, the oilcooler 530 can be mounted directly to the body 201.

As discussed in greater detail below, at least a section of each of theoil cooler supply passage 525 and the oil cooler outlet passage 535 isformed by the body 201 of the oil pan apparatus 200. Additionally, aswill be discussed in relation to the structural arrangement of FIGS.3-12, at least a section of each of the first and second pressure reliefpassages 526, 536 is also formed by the body 201 in certainarrangements.

Referring now to FIGS. 3-12 concurrently, a specific structuralarrangement of the oil pan apparatus 200 is disclosed. The oil panapparatus 200 comprises a body 201 having an upstanding wall 203 and afloor 204 that collectively form a basin 202. The body 201 furthercomprises a plurality of walls, posts and other structures that protrudefrom the floor 204 of the basin 202 or from the outer surface 205 of thebody 201. Walls, posts and other structures protruding from the floor204 of the basin 202 include, without limitation, a crankshaft supportpost 206, oil pump retaining wall 207 (FIG. 10), pressure relief valveretaining wall 208 (FIGS. 7, 8, and 10), and post-filter oil deliverypassage retaining wall 209 (FIG. 10). The purpose of these walls, postsand other structures will become apparent from the below discussionand/or will be readily discernible by one of skill in the art. Asmentioned above, the body 201 may be an integrally formed singlecomponent structure that can be formed by techniques such as, withoutlimitation, forging, machining, casting, injection molding, orcombinations thereof. In other arrangements, the body 201 may bemulti-component assembly wherein the components are coupled togethersubsequently.

Referring specifically now to FIGS. 3 and 9-11, oil gathers in the basin202 of the body 201 to form the oil reservoir 510. The oil pump 520(FIG. 10), which is exemplified as a trochoid-type pump, is locatedwithin the basin 202. Specifically, the oil pump 510 is located andmounted within the oil pump retaining wall 207. Operation of the oilpump 520 is driven by the crankshaft (not shown) via a pump gear 523which is operably engaged to the crankshaft. A rod 527 is non-rotatablycoupled to the pump gear 523 and extends through the inner rotor 528 ofthe oil pump 520. The rod 527 is non-rotatably coupled to the innerrotor 528 and has an end rotatably retained by the floor 204 of the body201.

The oil pump 520 comprises an inlet 521 that is in fluid communicationwith the oil reservoir 510 and an outlet 522 that is in fluidcommunication with the oil cooler supply passage 525. The oil coolersupply passage 525 comprises a first section 525A and a second section525B. The first section 525A of the oil cooler supply passage 525 isformed in the body 201 and extends from the outlet 522 of the oil pump520 and terminates as a first opening 210 in the outer surface 205 ofthe body 201. The second section 525B is formed by an oil cooler inletconduit 300. The oil cooler inlet conduit 300 comprises a first end 301fluidly coupled to the body 201 to be in fluid communication with thefirst opening 210. The oil cooler inlet conduit 300 also comprises asecond end 302 fluidly coupled to the inlet 531 of the oil cooler 530(shown in FIG. 2). Thus, the second section 525B of the oil coolersupply passage 525 is located exterior of the body 201.

When the oil pump 520 is operated/activated, oil is drawn into the inlet521 of oil pump and expelled via the outlet 522. The oil then flowssequentially through the first and second sections 525A, 525B of the oilcooler supply passage 525, and then into the oil cooler 530 for cooling(assuming that the first pressure relief valve 550 is in a closedstate).

Cooled oil exiting the outlet 532 of the oil cooler 530 flows into theoil cooler outlet passage 535. The oil cooler outlet passage 535comprises a pre-filter section 535A that extends from the outlet of theoil cooler 530 to a third opening 211 in the outer surface 205 of thebody 201. The third opening 211 is in fluid communication with the inletchamber 541 of the oil filter 540 (when an oil filter 540 is mounted tothe body 201 as shown in FIG. 2). The third opening 211 may be locatedin a depression 212 in the outer surface 205 of the body 201. When theoil filter 540 is mounted to the body 201 (discussed in greater detailbelow), the depression 212 is covered by the oil filter 540 so that theinlet chamber 541 of the oil filter 540 is in fluid communication withthe third opening 211. In such arrangements, the depression 212 may beconsidered as part of the oil cooler outlet passage 535, andspecifically part of the pre-filter section 535A of the oil cooleroutlet passage 535.

The pre-filter section 535A of the oil cooler outlet passage 535comprises a first section 537 and a second section 538. The firstsection 537 of the oil cooler outlet passage 535 is formed by an oilcooler outlet conduit 310 and, thus, extends exterior of the body 201.The oil cooler outlet conduit 310 comprises a first end 311 and a secondend 312. The first end 311 of the oil cooler outlet conduit 310 isfluidly coupled to the outlet 332 of the oil cooler 330. The second end312 of the oil cooler outlet conduit 310 is fluidly coupled to the body201 to be in fluid communication with a second opening 213 in the outersurface 205 of the body 201. Thus, the first section 537 of thepre-filter section 535A of the oil cooler outlet passage 535 extendsfrom the outlet 532 of the oil cooler 530 to the second opening 213 inthe outer surface 205 of the body 201.

The second section 538 of the pre-filter section 535A of the oil cooleroutlet passage 535 is formed in the body 201 and extends from the secondopening 213 to the third opening 211. As mentioned above, the thirdopening 211 is located in the outer surface 205 of the body 201 and isin fluid communication with the inlet chamber 541 of the oil filter 540(when the oil filter 540 is mounted to the body 201 as shown in FIG. 2).When the oil pump 520 is operating (and assuming that the first pressurerelief valve 550 is in a closed state), cooled oil exiting the outlet532 of the oil cooler 530 flows sequentially through the first andsecond sections 537, 538 of the pre-filter section 535A of the oilcooler supply passage 525.

Assuming that the second pressure relief valve 560 is in a closed state,once the cooled oil reaches the depression 212 and the inlet chamber 541of the oil filter 540, the cooled oil will pass through the filter media543 and into the outlet chamber 542 of the oil filter 540 (as shown FIG.2), thereby reaching the post-filter section 535B of the oil cooleroutlet passage 535. The post-filter section 535B of the oil cooleroutlet passage 535 is formed in the body 201 and extends from a fourthopening 214 in the outer surface 205 of the body 201 to a fifth opening215 in the outer surface 205 of the body 201.

The fourth opening 214 is in fluid communication with the outlet chamber542 of the oil filter 540 (when an oil filter 540 is mounted to the body201 as shown in FIG. 2). When the oil filter 540 is mounted to the body201 (discussed in greater detail below), the fourth opening 214 iscovered by the oil filter 540 so that the outlet chamber 542 of the oilfilter 540 is in fluid communication with the fourth opening 214. Thefifth opening 215, in the exemplified arrangement, is located on a wall216 of a central opening 217 of the crankshaft support post 206. Thewall 216 can be considered part of the outer surface 205 of the body201. After exiting the fifth opening 215, the oil is delivered to theportions 100 of the internal combustion engine to be lubricated.

The body 201 also comprises an oil filter mounting element 220 forfacilitating mounting of the oil filter 540 to the body 201. In theexemplified arrangement, the oil filter mounting element 220 comprises aboss 221. The boss 221 may comprises a threaded outer surface forfacilitating threaded coupling of the oil filter 540 thereto, as isknown in the art. The fourth opening 214 is located on a distal surfaceof the boss 221. Thus, the post-filtered section 535B of the oil cooleroutlet passage 535 extends through the boss 221.

The body 201 also comprises an annular rim 222 surrounding the boss 221.The annular rim 222 provides a surface to facilitate sealing of theinlet chamber 541 of the oil filter 540 relative to the externalenvironment. For example, when the oil filter 540 is threaded onto theboss 221, an O-ring gasket may become compressed between the housing 544and the annular rim 222, thereby sealing the inlet chamber 541 of theoil filter 540 relative to the external environment.

Each of the third and fourth openings 211, 214 is located adjacent to oron the oil filter mounting element 220. The third opening 211 ispositioned such that it will be in fluid communication with the inletchamber 541 of the oil filter 540 when the oil filter 540 is mounted tobody 201 using the oil filter mounting element 220. In the exemplifiedarrangement, the depression 212 (in which the third opening 211 islocated) is located on the outer surface 205 of the body 201 at aposition between the boss 221 and the annular rim 222. The third opening211 is positioned such that it will be in fluid communication with theoutlet chamber 542 of the oil filter 540 when the oil filter 540 ismounted to body 201 using the oil filter mounting element 220. In theexemplified arrangement, the fourth opening 214 is located on the filtermounting element 220.

Referring now to FIGS. 3-4, 7-8 and 10-12, the first pressure reliefvalve 550 and the second relief pressure relief valve 560 are locatedwithin the basin 202 of the body 201. The first and second pressurerelief valves 550, 560 are mounted within the pressure relief valveretaining wall 208 of the body 201.

The first pressure relief valve 550 is operably coupled to the oilcooler supply passage 525 as discussed above. In the exemplifiedarrangement, the first pressure relief valve 550 is operably coupled tothe first section 525A of the oil cooler supply passage 525, which isformed by the body 201. Specifically, the first pressure relief valve550 is operably coupled to the first section 525A of the oil coolersupply passage 525 by the first pressure relief passage 526. The firstpressure relief passage 526 is formed into the body 201 and is in fluidcommunication with the first section 525A of the oil cooler supplypassage 525. The first pressure relief passage 526 extends from thefirst section 525A of the oil cooler supply passage 525 to an outlet575. As best shown in FIGS. 8 and 10, the outlet 575 is divided into twooutlet openings 575A, 575B that open into the basin 202 and, thus, arein fluid communication with the oil reservoir 510 held therein. Thefirst pressure relief valve 550 is disposed within the first pressurerelief passage 526 and, thus, controls whether or not oil can flowthrough first pressure relief passage 526 to be expelled from the outlet575 and back into the oil reservoir 510 prior to passing through the oilcooler 530. In the exemplified, arrangement, opening of the firstpressure relief valve 550 allows oil in the oil cooler supply passage525 to return to the oil reservoir in the basin 202 without ever exitingthe body 201 (i.e., before exiting the first opening 210. As discussedin greater detail above, the first pressure relief valve 550 opens whenthe pressure in the oil cooler supply passage 525 reaches or exceeds thefirst predetermined pressure.

As mentioned above, one of the primary functions of the first pressurerelief valve 550 is to relieve pressure in the oil cooler supply passage525 during cold engine start-ups when the oil is cold and, thus, has ahigh viscosity. Therefore, in an effort to accommodate adequate flow ofthe highly viscous oil through the first pressure relief passage 526when the pressure within the oil cooler supply passage 525 meets orexceeds the first predetermined pressure (and the first pressure reliefvalve 550 is open), the outlet 575 of the first pressure relief passage526 is designed to have a first effective cross-sectional area that issufficiently large such that the cold oil (which has a high viscosity)can flow therethrough in a substantially unimpeded manner and does notcreate further pressure build-up in the oil cooler supply passage 525.In the exemplified arrangement, the first effective cross-sectional areais the sum of the cross-sectional areas of the two outlet openings 575A,575B.

The second pressure relief valve 560 is operably coupled to the oilcooler outlet passage 535 as discussed above. In the exemplifiedarrangement, the second pressure relief valve 560 is operably coupled tothe pre-filtered section 535A of the oil cooler outlet passage 535, andmore specifically to the second section 538 of the pre-filtered section535A of the oil cooler outlet passage 535. As exemplified, the secondpressure relief valve 560 is operably coupled to the second section 538of the pre-filtered section 535A of the oil cooler outlet passage 535 bythe second pressure relief passage 536. The second pressure reliefpassage 536 is formed by the body 201 and is in fluid communication withthe second section 538 of the pre-filtered section 535A of the oilcooler outlet passage 535. The second pressure relief passage 536 is influid communication with the second section 538 of the pre-filteredsection 535A of the oil cooler outlet passage 535 via a sixth opening225 located in the depression 212. Thus, the second pressure reliefpassage 536 is in fluid communication with cooled oil entering thedepression 212 via the third opening 211 at a position upstream of theoil filter 540.

The second pressure relief passage 536 extends from the second section538 of the pre-filtered section 535A of the oil cooler outlet passage535 to an outlet 576. As best shown in FIGS. 8 and 10, the outlet 576opens into the basin 202 and, thus, is in fluid communication with theoil reservoir 510 held therein. The second pressure relief valve 560 isdisposed within the second pressure relief passage 536 and, thus,controls whether or not oil can flow through second pressure reliefpassage 536 to be expelled from the outlet 576 and back into the oilreservoir 510 after passing through the oil cooler 530 (and prior toflowing through the filter media 543). As discussed in greater detailabove, the second pressure relief valve 560 opens when the pressure inthe second section 538 of the pre-filtered section 535A of the oilcooler outlet passage 535 reaches or exceeds the second predeterminedpressure. Opening so of the second pressure valve 560 allows oil thathas passed through the oil cooler 530 (but not yet passed through theoil filter 540 in the exemplified arrangement), to return to the oilreservoir in the basin 202 without having to pass through the filtermedia 543 and/or being supplied to the portions 100 of the internalcombustion engine to be lubricated. Thought of another way, the secondpressure relief valve 560 allows cooled oil that has passed through theoil cooler 530 to return to the oil reservoir 510 in the basin 202without passing through the fourth opening 514.

As mentioned above, one of the primary functions of the second pressurerelief valve 560 is to relieve pressure in the oil circuit during normalengine operating conditions while at the same time maximizing the amountof the oil that passes through the oil cooler 530. Thus, the secondpredetermined pressure is selected to be sufficiently less than thefirst predetermined pressure so that the second pressure relief valve560 opens well before the first pressure relief valve 550 opens. Thus,pressure relief within the oil circuit is achieved while still ensuringthat the oil is being cooled. In the exemplified arrangement, the secondeffective cross-sectional area of the outlet 576 of the second pressurerelief passage 536 is less than the first effective cross-sectional areaof the outlet 575 of the first pressure relief passage 526. In theory,full pump output minus bearing needs must pass through outlet 575 whenthe oil is cold, while full pump output minus bearing needs must passthrough outlet 576 when the oil is hot.

Referring now to FIGS. 3-4, 7-8 and 13A-B, the first and second pressurerelief valves 550, 560 are check valves. The first pressure relief valve550 generally comprises a first valve seat 551, a first valve body 552,and a first resilient element 553 that biases the first valve body 552into the first valve seat 551 to close the first pressure relief valve550. Similarly, the second pressure relief valve 560 comprises a secondvalve seat 561, a second valve body 562, and a second resilient element563 that biases the second valve body 562 into the second valve seat 561to close the second pressure relief valve 560.

In the exemplified arrangement, each of the first and second valvebodies 552, 562 is a ball. Moreover, each of the first and secondresilient elements 553, 563 is a compression coil spring. The first andsecond valve bodies 552, 562 and the first and second resilient elements553, 563 may take on other structures in other arrangements, the exactnature of which will depend on the type and structure of the valvesselected for the first and second pressure relief valves 550, 560. Forexample, other suitable structures for the first and second valve bodies552, 562 may include, without limitation, piston-like structures,plungers, plates, conical-like structures). Other suitable structuresfor the first and second resilient elements 553, 563 include other typesof variable springs (including tension springs, leaf springs, flatsprings, cantilever springs, conical springs, V-springs, bodies formedof an elastomeric material (including rubbers and thermoplasticelastomers). Alternatively, any other means of applying a force that isnot a fixed or rigid body may be used, such as a hydraulic piston or anelectromagnet.

Each of the first and second pressure relief valves 550, 560 arenormally biased into the closed state. In the exemplified embodiment,this is achieved by the first and second resilient elements 553, 563being under compression between a bottom surface 241 of a plate 240 andthe first and second valve bodies 552, 562 respectively. The plate 240,in the exemplified arrangement, is a cover plate for the oil pump 520.In other arrangements, the plate 240 may be a different part of theinternal combustion engine. For example, the plate 240 could be a wall,floor or other structure of the body 201, or another plate locatedwithin the housing of the engine block.

The cover plate 240 is secured to the oil pump retaining wall 207 by aplurality of fasteners 255. When the plate 240 is secured to the oilpump retaining wall 207, each of the first and second resilient elements553, 563 are under compression due to being axially constrained by thebottom surface 241 of the cover plate 240 at an upper end thereof andthe first and second valve bodies 251, 261 at a lower end thereof. Thus,the first and second pressure relief valves 550, 560 are normally biasedinto the closed state.

As discussed above, the first pressure relief valve 550 is configured toopen at a first predetermined pressure while the second pressure reliefvalve 560 is configured to open at a second predetermined pressure.Thus, the first and second pressure relief valves 550, 560 havedifferent pressure settings, despite the first and second resilientelements 553, 563 being identical to one another (which in theexemplified arrangement are identical compression coil springs). Priorto being constrained (and compressed) by the cover plate 240, the firstand second resilient elements 553, 563 have the same length L (as shownin FIG. 13B). Once the cover plate 240 is secured to the to the oil pumpretaining wall 207, the first resilient element 553 is compressed to afirst length L1 and the second resilient element 563 is compressed to asecond length L2, wherein the first length L1 is less than the secondlength L2 (as shown in FIG. 13A). The second length L2 may be less thanthe length L.

As a result of the first length L1 being less than the second length L2,the first pressure relief valve 550 has a pressure setting that isgreater than the pressure setting of the second pressure relief valve560 (i.e., the first predetermine pressure is greater than the secondpredetermined pressure). Thus, despite identical resilient elements 553,563 being used in the first and second pressure relief valves 550, 560,different pressure settings are achievable. As will be noted from FIG.13A, the bottom surface 241 of the cover plate 240 comprises atopographical feature 245 that creates the difference between the firstlength L1 and the second length L2. The topographical feature 245, inthe exemplified arrangement, is a detent (as viewed from the bottomsurface 241) that is contacted by the second resilient element 563.Because the second resilient element 563 extends into and contacts thefloor of the detent 245 and the first resilient element 553 contacts themajor surface of the bottom surface 241, the second resilient element563 is compressed a smaller amount as compared to the first resilientelement 553 when the cover plate 240 is secured into place.

While the topographical feature 245 is exemplified as a detent, thetopographical feature 245 in other arrangement may be a protuberancethat extends from the bottom surface 241 of the plate 240. In such anarrangement, the topographical feature 245 may be repositioned on theplate 240 so as to come into contact with the first resilient element553, rather than the second resilient element 563. As a result, theprotuberance will result in the first resilient element 553 beingcompressed a greater amount than the second resilient element 563,wherein the second resilient element 563 which may contact the majorsurface of the bottom surface 240.

In still other arrangements, multiple topographical features 245 may beprovided on the bottom surface 241 of the plate 240 such that each ofthe first and second resilient elements 553, 563 may contact a differentone of the topographical features 245. In such an arrangement, thetopographical features 245 are configured to have a relative differencein axial height (measured relative to the compression axes of the firstand second resilient elements 553, 563). As used herein, a steppedsurface qualifies as a topographical feature 245.

In further arrangements, the difference between the first and secondlengths L1, L2 can be achieved by using a cover plate 240 that has abottom surface that is free of topographical features 245 by either: (1)angling the plate 240 relative to the compression axes of the first andsecond resilient elements 553, 56; or (2) positioning the first andsecond seats 551, 561 at different depths within the body 201 from thebottom surface 241 of the plate 240.

As used throughout, ranges are used as shorthand for describing each andevery value that is within the range. Any value within the range can beselected as the terminus of the range. In addition, all references citedherein are hereby incorporated by referenced in their entireties. In theevent of a conflict in a definition in the present disclosure and thatof a cited reference, the present disclosure controls.

While the foregoing description and drawings represent some examplesystems, it will be understood that various additions, modifications andsubstitutions may be made therein without departing from the spirit andscope and range of equivalents of the accompanying claims. Inparticular, it will be clear to those skilled in the art that thepresent invention may be embodied in other forms, structures,arrangements, proportions, sizes, and with other elements, materials,and components, without departing from the spirit or essentialcharacteristics thereof. In addition, numerous variations in themethods/processes. One skilled in the art will further appreciate thatthe invention may be used with many modifications of structure,arrangement, proportions, sizes, materials, and components andotherwise, used in the practice of the invention, which are particularlyadapted to specific environments and operative requirements withoutdeparting from the principles of the present invention. The presentlydisclosed embodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingdefined by the appended claims and equivalents thereof, and not limitedto the foregoing description or embodiments. Rather, the appended claimsshould be construed broadly, to include other variants and embodimentsof the invention, which may be made by those skilled in the art withoutdeparting from the scope and range of equivalents of the invention.

What is claimed is:
 1. A valve system comprising: a fluid pathway fortransporting a fluid; a first valve operably coupled to the fluidpathway, the first valve comprising a first resilient element; a secondvalve operably coupled to the fluid pathway, the second valve comprisinga second resilient element that is substantially identical to the firstresilient element; wherein, when the first valve is in a closed state,the first resilient element is compressed to a first length so that thefirst valve opens at a first pressure; and wherein, when the secondvalve is in a closed state, the second resilient element is compressedto a second length so that the second valve opens at a second pressure,the first length is less than the second length such that the secondpressure is less than the first pressure.
 2. The valve system of claim 1further comprising: the first valve comprising a first valve seat and afirst valve body, the first resilient element biasing the first valvebody into the first valve seat to close the first valve; and the secondvalve further comprising a second valve seat and a second valve body,the second resilient element biasing the second valve body into thesecond valve seat to close the second valve.
 3. The valve system ofclaim 2 wherein the first and second valve seats are structurallyidentical to one another.
 4. The valve system of claim 2 wherein thefirst and second valve bodies are structurally identical to one another.5. The valve system of claim 1 further comprising: a body; the fluidpathway comprising a first section formed in the body and a secondportion formed in the body; and the first valve operably coupled to thefirst section and the second valve operably coupled to the secondsection.
 6. The valve system of claim 5 wherein the body is a portion ofa housing of an engine block.
 7. The valve system of claim 5 wherein thefirst valve comprises a first valve seat integrally formed as part ofthe body and the second valve comprises a second valve seat integrallyformed as part of the body.
 8. The valve system of claim 1 furthercomprising: a cover comprises a topographical feature; and the first andsecond resilient elements compressed by the cover, one of the first orsecond resilient elements contacting the topographical feature, therebyaccounting for the difference between the first length and the secondlength.
 9. The valve system of claim 1 wherein the first valve comprisesa first valve seat at a first depth and the second valve comprises asecond valve seat at a second depth, the second depth being differentthan the first depth, thereby accounting for the difference between thefirst length and the second length.
 10. The valve system of claim 1wherein the first pressure relief valve has an outlet having a firsteffective cross-sectional area and the second relief valve having anoutlet having a second effective cross-sectional area that is differentthan the first effective cross-sectional area.
 11. A valve systemcomprising: a fluid pathway for transporting a fluid; a first valveoperably coupled to the fluid pathway, the first valve comprising afirst resilient element having a first spring constant; a second valveoperably coupled to the fluid pathway, the second valve comprising asecond resilient element having a second spring constant; the secondspring constant being substantially the same as the first springconstant; wherein, when the first valve is in a closed state, the firstresilient element is deformed a first degree so that the first valveopens at a first pressure; and wherein, when the second valve is in aclosed state, the second resilient element is deformed a second degreeso that the second valve opens at a second pressure that is differentthan the first pressure.
 12. The valve system of claim 11 furthercomprising: the first valve comprising a first valve seat and a firstvalve body, the first resilient element biasing the first valve bodyinto the first valve seat to close the first valve; and the second valvefurther comprising a second valve seat and a second valve body, thesecond resilient element biasing the second valve body into the secondvalve seat to close the second valve.
 13. The valve system of claim 11further comprising: a body; the fluid pathway comprising a first sectionformed in the body and a second portion formed in the body; and thefirst valve comprises a first valve seat integrally formed as part ofthe body and the second valve comprises a second valve seat integrallyformed as part of the body.
 14. The valve system of claim 13 wherein thebody is a portion of a housing of an engine block.
 15. The valve systemof claim 11 further comprising: a cover comprises a topographicalfeature; and the first and second resilient elements compressed by thecover, one of the first or second resilient elements contacting thetopographical feature, thereby accounting for the difference between thefirst length and the second length.
 16. The valve system of claim 11wherein the first valve comprises a first valve seat at a first depthand the second valve comprises a second valve seat at a second depth,the second depth being different than the first depth, therebyaccounting for the difference between the first and second degrees ofdeformation.
 17. A valve system comprising: a monolithic body; a fluidpathway for transporting a fluid, the fluid pathway comprising a firstsection formed in the monolithic body and a second section formed in themonolithic body; a first valve operably coupled to the first section ofthe fluid pathway, the first valve comprising a first valve seatintegrally formed as part of the monolithic body; and a second valveoperably coupled to the second section of the fluid pathway, the secondvalve comprising a second valve seat integrally formed as part of themonolithic body; a cover comprising a topographical feature; the firstvalve comprises a first resilient element and the second valvecomprising a second resilient element; and the first and secondresilient elements compressed by the cover, one of the first or secondresilient elements contacting the topographical feature, therebyaccounting for a difference in length between the first and secondresilient elements.
 18. The valve system of claim 17 wherein themonolithic body is a portion of an oil pan configured to be coupled toan engine block.
 19. A valve system comprising: a body; a fluid pathwayfor transporting a fluid, the fluid pathway comprising a first sectionformed in the body and a second portion formed in the body; a firstvalve operably coupled to the first section of the fluid pathway, thefirst valve comprising a first valve seat integrally formed as part ofthe body; and a second valve operably coupled to the second section ofthe fluid pathway, the second valve comprising a second valve seatintegrally formed as part of the body; wherein the first valve seatbeing at a first depth within the body and the second valve seat beingat a second depth within the body.